1. Field of the Invention
The Invention relates to a water jet device for separating a biological structure.
2. Brief Description of the Background of the Invention Including Prior Art
Water jet devices and their application in the medical field are known in many variations. The advantage of water jet devices relative to mechanical surgical devices and methods is based first in a more gentle treatment of the biological structures.
In general such devices are associated with the disadvantage that the separating liquid cannot be maintained sterile and that the pressure of the separating medium exiting is subject to relatively large variations.
Now a water jet device is described in the German printed patent document DE 4200976, which avoids these disadvantages and which comprises essentially a pressure loaded piston cylinder device, wherein a receiver container for the separating medium is fitted into the cylinder space of the piston cylinder device. The receiver container for the separating medium is here a cartridge and is connected to a separating nozzle through a line. The separating medium is kept sterile by the separation of pressure medium and separating medium and by the stable cartridge and the pressure situations of the separating medium remain constant and reproducible.
This assures a water jet in a laminar region and thereby an advantageous sharp edge feature of the water jet.
A similar water jet device is known from the U.S. Pat. No. 5,037,431, wherein the water jet device is also furnished with a separating nozzle, wherein the separating nozzle is disposed at the distal end of the supply line and exhibits a circular cross-section.
All water jet devices known up to now are however associated with the disadvantage that the water jet impinges onto the biological structure bundled and with its total cross-section. For example soft tissue easily yields to this pressure such that a relatively wide and also frequently dirty separating cut results. The biological structure is thereby exerted and loaded excessively. A further refinement of the water jet by a further reduction of the nozzle diameter is technically limited. Such a water jet is also difficult to apply under liquid, since such water jet exhibits disintegration appearances already shortly after the exiting out of the nozzle and since the separating sharpness of the water jet is lost. In particular cases an increased destruction of the biological structure is associated with a necessary increase of the flow pressure, since in addition the separating force of the water jet is determined exclusively by the size of the flow pressure freely selectable by the operator.